CN109690727B

CN109690727B - Workpiece processing equipment

Info

Publication number: CN109690727B
Application number: CN201780055593.3A
Authority: CN
Inventors: 葛兰·Fr·吉尔克里斯特; 梁树荣
Original assignee: Varian Semiconductor Equipment Associates Inc
Current assignee: Varian Semiconductor Equipment Associates Inc
Priority date: 2016-09-12
Filing date: 2017-08-10
Publication date: 2020-11-06
Anticipated expiration: 2037-08-10
Also published as: JP6768147B2; JP2019530149A; TW201812904A; KR102241017B1; US20180076007A1; CN109690727A; US10141161B2; WO2018048566A1; TWI723208B; KR20190040371A

Abstract

The invention discloses a workpiece processing device capable of independently controlling the extraction angle of charged ions and the extraction angle of reactive neutral particles. The apparatus includes an extraction plate having an extraction aperture through which charged ions pass. The extraction angle of the charged ions can be determined using plasma sheath modulation and electric field. The extraction plate further includes one or more neutral substance channels separated from the extraction aperture through which the reactive neutral particles pass at a selected extraction angle. The geometry of the neutral species channel determines the extraction angle of the reactive neutral species. The neutral mass passage may further include a suppressor for reducing the number of charged ions passing through the neutral mass passage. The apparatus may be used in various applications, such as directional reactive ion etching.

Description

Workpiece processing equipment

Technical Field

Embodiments of the invention relate to angle control of a neutral ion beam, and more specifically to an apparatus that forms a charged ion beam and a neutral ion beam for use in a directional reactive ion etching process.

Background

There are many technical challenges in fabricating advanced three-dimensional semiconductor structures with complex surface topology (complex surface topography) and high packing density. As the critical dimensions and pitch of the devices decrease, the aspect ratio of the features increases. For example, this tendency results in deep but very narrow trenches on the surface of the workpiece. These trenches may be formed using a technique known as Reactive Ion Etching (RIE) or RIE. The trimming and formation of the various trench liner materials may be performed using a technique known as Directional Reactive Ion Etching (DRIE). A specified portion of the walls of these trenches are selectively etched with precise angular control. Angular control of the ion beam may be achieved by manipulating the electric field used to focus the ions in a particular direction.

The charged ion beam can be supplemented with reactive neutral particles to increase the etch rate of the reactive ion etch. However, reactive neutrals cannot be controlled using an electric field. Thus, while the angle of the charged ion beam can be precisely controlled, this approach is not suitable for reactive neutrals. The problem of lack of angular control of reactive neutrals becomes more pronounced as the angle for directional reactive ion etching decreases (i.e., becomes closer to perpendicular to the workpiece). Reactive neutral particles are defined as, but not limited to, those radicals/atoms that are highly reactive with some material on the workpiece. For example, under the right process conditions, chlorine has a high reaction rate with TiN, but with SiO₂With a very low reaction rate. These reactive neutral particles are used to etch portions of the workpiece without affecting other components. The speed of the etching process can be compromised if the angle at which the reactive neutrals are directed toward the workpiece cannot be controlled. In some embodiments, failure to control the angle at which the reactive neutrals are directed toward the workpiece can make it difficult to obtain prescribed features on the workpiece.

It would therefore be advantageous if there were a device that could control the angle at which the reactive neutrals are directed toward the workpiece. Furthermore, it would be advantageous if there were a device that could also control the angle at which charged ions are directed towards the workpiece. Such an apparatus may be advantageous in certain applications, such as directional reactive ion etching.

Disclosure of Invention

The invention discloses a workpiece processing device capable of independently controlling the extraction angle of charged ions and the extraction angle of reactive neutral particles. The apparatus includes an extraction plate having an extraction aperture through which charged ions pass. The extraction angle of the charged ions can be determined using plasma sheath modulation and electric field. In certain embodiments, the extraction plate further comprises one or more neutral substance channels separated from the extraction aperture through which the reactive neutral particles pass at the selected extraction angle. The geometry of the neutral species channel determines the extraction angle of the reactive neutral species. The neutral mass passage may further include a suppressor for reducing the number of charged ions passing through the neutral mass passage. The apparatus may be used in various applications, such as directional reactive ion etching.

According to one embodiment, a workpiece processing apparatus is disclosed. The workpiece processing apparatus includes: a plasma generator; a plasma chamber; and an extraction plate having a first opening and a second opening; wherein charged ions are extracted through the first opening at a first selected extraction angle and reactive neutral particles pass through the second opening at a second selected extraction angle, wherein the second opening is different from the first opening. In certain embodiments, the second aperture includes a suppressor for minimizing charged ions passing through the second aperture. The suppressor may be an electrically biased grid (electrically biased grid), an electrically biased cup (electrically biased cup), or a screen. In certain embodiments, the second selected extraction angle is determined by an inclination of the second aperture relative to a plane orthogonal to the extraction plate. In certain embodiments, the angular distribution of reactive neutrals centered at the second selected extraction angle is determined by an aspect ratio of the second aperture, the aspect ratio being defined as the length of the second aperture through the extraction plate divided by the height of the second aperture. In certain embodiments, a blocker is disposed in the plasma chamber. In certain embodiments, the reactive neutral species are formed in a remote neutral species generator distinct from the plasma chamber and are transported to the second opening.

According to another embodiment, a workpiece processing apparatus is disclosed. The workpiece processing apparatus includes: a plasma generator; a plasma chamber; and an extraction plate through which the charged ions and reactive neutral particles are extracted, wherein the workpiece processing apparatus extracts charged ions from the plasma chamber at a first selected extraction angle using a first mechanism through an extraction aperture disposed in the extraction plate and extracts reactive neutral particles from the plasma chamber at a second selected extraction angle using a second mechanism. In certain embodiments, the first mechanism comprises a plasma sheath modulating or electric field proximate the extraction aperture. In certain embodiments, the second mechanism comprises a geometric configuration of neutral species channels. In certain embodiments, the neutral substance channel is disposed in the extraction plate. In certain embodiments, the neutral species passage is disposed in a blocker disposed within the plasma chamber proximate the extraction aperture.

According to another embodiment, a workpiece processing apparatus is disclosed. The workpiece processing apparatus includes: a plasma generator; a plasma chamber; and an extraction plate comprising an extraction aperture; wherein the workpiece processing apparatus extracts charged ions as an ion beam through the extraction aperture at a first selected extraction angle using plasma sheath modulation or an electric field; and wherein the reactive neutral species pass through the neutral species channel at a second selected extraction angle. The neutral substance channel may be provided in the extraction plate or may be provided in a blocker provided within the plasma chamber adjacent to the extraction aperture. In certain embodiments, the neutral species channel is the extraction aperture.

Drawings

For a better understanding of the present invention, reference is made to the accompanying drawings, which are incorporated herein by reference, and in which:

FIG. 1 is a workpiece processing apparatus according to one embodiment.

Fig. 2 is an enlarged view of an extraction plate of the workpiece processing apparatus shown in fig. 1.

Fig. 3A to 3C show three embodiments of neutral passage with suppressors.

Fig. 4A to 4C show an embodiment of a neutral substance channel with a collimated channel.

Fig. 5A to 5C show various embodiments of neutral substance passages as viewed from a workpiece.

Fig. 6A to 6B show embodiments with adjustable neutral mass channels.

Fig. 7A-7B illustrate representative workpieces that may be processed using the apparatus shown in fig. 1.

Fig. 8A-8I illustrate various configurations of blockers and extraction apertures and resulting extraction angles.

Fig. 9 is an enlarged view of an extraction plate and a stopper of a workpiece processing apparatus according to another embodiment.

Fig. 10 is an enlarged view of an extraction plate of a workpiece processing apparatus according to another embodiment.

Detailed Description

Fig. 1 illustrates a first embodiment of a workpiece processing apparatus 10 for controlling the angle at which charged and reactive neutral particles are directed toward a workpiece 90. The workpiece processing apparatus 10 includes a plasma chamber 30, the plasma chamber 30 being defined by a plurality of chamber walls 32.

An antenna 20 is disposed outside the plasma chamber 30, adjacent to the dielectric window 25. The dielectric window 25 may also form one of the walls defining the plasma chamber 30. The antenna 20 is electrically connected to a Radio Frequency (RF) power supply 27, and the RF power supply 27 supplies an alternating voltage to the antenna 20. The voltage may have a frequency of, for example, 2MHz or greater than 2 MHz. Although dielectric window 25 and antenna 20 are shown on one side of plasma chamber 30, other embodiments may exist. For example, the antenna 20 may surround a chamber wall 32 of the plasma chamber 30 or be disposed on top of the plasma chamber 30. The chamber walls 32 of the plasma chamber 30 may be made of an electrically conductive material (e.g., graphite). The chamber walls 32 may be biased to an extraction voltage, for example, by an extraction power supply 80. The extraction voltage may be, for example, 1kV, but other voltages are within the scope of the invention.

The workpiece processing apparatus 10 includes an extraction plate 31 having an extraction aperture 35. The extraction plate 31 may form another wall for defining the plasma chamber 30. The extraction aperture 35 may be about 320mm in the X-direction and 30mm in the Y-direction, but may be of other dimensions. The extraction plate 31 may have a thickness in the Z-direction of between 5mm and 10mm, but may also be of other dimensions. This extraction plate 31 may be arranged on the side of the plasma chamber 30 opposite the dielectric window 25, but other configurations may also be present. In certain embodiments, the extraction plate 31 may be composed of an insulating material. For example, the extraction plate 31 may comprise quartz, sapphire, alumina, or similar insulating materials. The use of an insulating material may enable modulation of the plasma sheath which affects the angle at which charged ions exit the extraction aperture 35. In other embodiments, the extraction plate 31 may be composed of a conductive material.

A blocker 37 may be provided on the interior of the plasma chamber 30 proximate the extraction aperture 35. In certain embodiments, the stop 37 is constructed of an insulating material. The stopper 37 may be about 3mm to 5mm in the Z direction and have the same size as the extraction aperture 35 in the X direction. The length of the stopper 37 in the Y direction may be changed to achieve a target extraction angle.

The location and size of the blocker 37 and the size and shape of the edge of the extraction aperture 35 may define the boundary of the plasma sheath within the plasma chamber 30. The boundary of the plasma sheath in turn determines the angle at which the charged ions intersect the plasma sheath and exit via the extraction aperture 35. In certain embodiments, the stoppers 37 may comprise a conductive material. In these embodiments, the conductive material on the stopper 37 may be biased to form an electric field near the extraction aperture 35. The electric field may also be used to control the angle at which charged ions exit through the extraction aperture 35. A blocker 37 (such as that shown in fig. 1) located between the interior of the plasma chamber 30 and the extraction opening 35 may form a bimodal extraction angle profile. In other words, the charged ions may exit the extraction aperture 35 at an angle of + θ ° or- θ °, where θ is determined by the size and position of the blocker 37, the width of the extraction aperture 35, and the electric field near the extraction aperture.

Although fig. 1 shows the stopper 37, in other embodiments, the stopper 37 is not employed.

A workpiece 90 is disposed on the near side and the outside of the extraction plate 31 of the plasma chamber 30. In some embodiments, the workpiece 90 may be within about 1cm of the extraction plate 31 in the Z-direction, but may be other distances. In operation, the antenna 20 is powered using an RF signal from the RF power supply 27 to inductively couple energy into the plasma chamber 30. This inductively coupled energy excites feed gas (feed gas) introduced from gas storage vessel 70 via gas inlet 71, thereby generating a plasma. Although fig. 1 shows an antenna, other plasma generators may be used with the present invention. For example, a capacitively coupled plasma generator may be used.

The plasma within the plasma chamber 30 may be biased to a voltage applied to the chamber walls 32 by the extraction power supply 80. A workpiece 90 (which may be disposed on a platen 95) is disposed proximate to the extraction plate 31. Platen 95 may be electrically biased by a bias power supply 98. The potential difference between the plasma and the workpiece 90 causes charged ions in the plasma to accelerate in the form of one or more ribbon ion beams through the extraction opening 35 and toward the workpiece 90. In other words, when the voltage applied by the extraction power supply 80 is more positive than the bias voltage applied by the bias power supply 98, positive ions are attracted toward the workpiece 90. Thus, to extract positive ions, the chamber walls 32 may be biased to a positive voltage while the workpiece 90 is biased to a smaller positive voltage, ground, or to a negative voltage. In other embodiments, the chamber wall 32 may be grounded while the workpiece 90 is biased to a negative voltage. In still other embodiments, the chamber walls 32 may be biased to a negative voltage while the workpiece 90 is biased to a more negative voltage.

Ribbon ion beam 60 (see fig. 2) may be at least as wide as workpiece 90 in one direction (e.g., the X-direction) and may be much narrower than workpiece 90 in the orthogonal direction (or the Y-direction). In one embodiment, the extracted ribbon ion beam 60 may be about 1mm in the Y-direction and 320mm in the X-direction.

In addition, the platen 95 and workpiece 90 may be translated relative to the extraction aperture 35 to expose different portions of the workpiece 90 to the ribbon ion beam 60. The process in which the workpiece 90 is translated to expose the workpiece 90 to the ribbon ion beam 60 is referred to as a "pass". One operation may be performed by translating platen 95 and workpiece 90 while maintaining the position of plasma chamber 30. The speed at which the workpiece 90 translates relative to the extraction aperture 35 can be referred to as the workpiece scan speed. In some embodiments, the workpiece scan speed may be about 100mm/sec, although other speeds may be used. In another embodiment, the plasma chamber 30 may be translated while the workpiece 90 remains stationary. In other embodiments, both plasma chamber 30 and workpiece 90 may be translated. In some embodiments, the workpiece 90 is moved in the Y direction relative to the extraction aperture 35 at a constant workpiece scanning speed to expose the entire workpiece 90 to the ribbon ion beam 60 for the same period of time.

As described above, the charged ions are directed at the workpiece 90 at a predetermined angle using the extraction aperture 35. As described above, the plasma sheath and the electric field are used to control the angle at which charged ions exit the extraction aperture 35. However, the reactive neutrals are not affected by any of these mechanisms and therefore leave the extraction opening in a random manner. The reactive neutral particles travel in a straight line until the reactive neutral particles collide with other particles or structures. For example, the reactive neutrals may collide with the blocker 37, the extraction plate 31, or with other ions or reactive neutrals. Collisions between reactive neutrals, including radicals and atoms, can cause recombination to form molecules that are typically much less reactive or impractical for use in directional reactive ion etching processes. Thus, most of the reactive neutrals exit the extraction opening at high extraction angles. Throughout this disclosure, the extraction angle is referenced to a plane perpendicular to the workpiece 90. Thus, an extraction angle of 0 ° refers to a path perpendicular to the surface of the workpiece 90, while an extraction angle of 90 ° is a path parallel to the surface of the workpiece 90.

The angle of extraction of reactive neutrals can be controlled to some extent by the placement and size of the blocker 37, however, the range and accuracy of such angular control is limited.

Therefore, in order to better control the extraction angle of the reactive neutral particles, one or more neutral substance channels 100 may be provided in the extraction plate 31.

The neutral substance passage 100 may be provided on opposite sides of the extraction opening 35 in the extraction plate 31. Thus, there are at least two neutral particle channels 100 that can be configured to direct reactive neutral particles at two angles toward the workpiece 90, which can correspond to a bimodal distribution of charged ions exiting the extraction aperture 35. Of course, in other embodiments, only one neutral substance passage 100 may be provided on the extraction plate 31.

Fig. 2 shows an enlarged view of the extraction plate 31, the stopper 37 and the workpiece 90 according to one embodiment. When the blocker 37 is employed, the charged ions exit the extraction aperture 35 in the form of two ribbon ion beams 60. The neutral substance passage 100 facilitates the exit of reactive neutral particles from the plasma chamber 30 in the form of a neutral particle beam 101. The reactive neutrals exiting the neutrals channel 100 have an extraction angle range defined by a central extraction angle and angular distribution. The narrow distribution means that most of the reactive neutrals travel in a path close to the central extraction angle.

The central extraction angle of the reactive neutrals is controlled by the direction of the neutrals channel 100. For example, fig. 2 shows each of the neutral substance channels 100 being slightly inclined toward the extraction aperture 35. The horizontal neutral passage may have a central extraction angle of 0 °. The central extraction angle increases as the neutral substance passage 100 is inclined away from the plane orthogonal to the extraction plate 31. The distribution of the extraction angles of the reactive neutrals may be defined by the geometric configuration of the neutrals channel 100. The ratio of the dimension of the neutral substance passage 100 in the Z direction to the dimension of the neutral substance passage 100 in the Y direction may be referred to as the aspect ratio of the neutral substance passage 100. The neutral substance passage 100 having a high aspect ratio has a narrower extraction angle distribution than the neutral substance passage having a low aspect ratio. In certain embodiments, an aspect ratio of at least 5 may be advantageous. In other embodiments, the aspect ratio may be greater than 10.

In certain embodiments, the neutral mass passage 100 may be about 10mm from the extraction aperture 35 in the Y-direction. The neutral substance passage 100 may have a size in the X direction substantially equal to a size of the extraction opening 35 in the X direction.

In certain embodiments, it may be advantageous to pass only reactive neutrals through the neutrals channel 100. This can be achieved by introducing a suppressor into the neutral mass passage 100.

Fig. 3A to 3C show different embodiments of the neutral substance passage 100 including the suppressor. The suppressor serves to suppress the passage of charged ions through the neutral mass channel 100. In certain embodiments, this is accomplished by repelling charged ions from the neutral mass passage 100. In other embodiments, this is accomplished by neutralizing any charged ions entering the neutral mass passage 100.

Fig. 3A shows an embodiment of a neutral material passage 100 comprising an electrically biased grid 200 disposed within an insulator 210. The insulator 210 may isolate the electrically biased grid 200 from the extraction plate 31. If the extraction plate 31 is made of an insulating material, the insulator 210 may not be employed. The biased grid 200 may be comprised of a conductive material (e.g., a metal such as tungsten). A positive voltage may be applied by the grid power supply 220. The voltage may be selected to repel positive ions back into the interior of the plasma chamber 30. The electrically biased grid 200 can be disposed anywhere in the neutral material passage 100. In certain embodiments, an electrically biased grid 200 may be disposed in the neutral mass passage 100 near the interior of the plasma chamber 30 to minimize collisions within the neutral mass passage 100. Other embodiments include baffles (baffles) that operate at a bias voltage sufficient to repel charged ions back into the plasma chamber 30.

Fig. 3B shows an embodiment of the neutral mass passage 100 including an electrically biased cup 250, the cup 250 being disposed within an insulator 260. The insulator 260 may isolate the electrically biased cup 250 from the extraction plate 31. If the extraction plate 31 is made of an insulating material, the insulator 260 may not be employed. The electrically biased cup 250 may be constructed of an electrically conductive material (e.g., a metal such as tungsten). A positive voltage may be applied by the cup power supply 270. The voltage may be selected to repel positive ions back into the interior of the plasma chamber 30.

Fig. 3C shows an embodiment of the neutral passage 100 including a screen 240. In this embodiment, the screen 240 receives charged ions and reactive neutrals from the plasma chamber 30, but causes the ions to be neutralized by surface collisions before exiting the neutrals passage 100 toward the workpiece. The material of the screen 240 is selected such that reactive neutral particles including radicals do not recombine on the walls of the screen 240. The side of the screen facing the plasma chamber 30 may be solid and the aspect ratio of the channel may be large enough so that the ions do not have a line of sight path to the workpiece and do not collide with the top of the screen or the side walls of the neutral passage 100 to neutralize the ions.

The embodiment of fig. 3A-3C may be used with the extraction plate 31 of fig. 1 and 2. In other words, the extraction plate 31 may include an extraction aperture 35 through which the charged ions are directed toward the workpiece 90 at a first selected extraction angle. The extraction plate 31 may also include one or more neutral substance channels 100 through which reactive neutral particles are directed at the workpiece 90 at a second selected extraction angle. As described above, the first selected extraction angle may be determined by modulating the plasma sheath or by using an electric field. The second selected extraction angle may be determined by the geometry of the neutral mass passage 100. Although the first selected extraction angle may be the same as the second selected extraction angle, it should be noted that other embodiments exist. For example, the first selected angle and the second selected angle may differ by an attraction to charged ions that the reactive neutral particles do not experience. By using different mechanisms to determine the first and second selected extraction angles, these extraction angles can be independently controlled.

It should be noted that some reactive neutrals may also exit the plasma chamber 30 via the extraction aperture 35. However, the angle at which these reactive neutrals exit may not be controlled to the same magnitude as the angle at which the reactive neutrals exit the neutrals channel 100. For example, the reactive neutral particles exiting the extraction aperture 35 can have a wide distribution, and can also have an extraction angle that is greater than the second selected extraction angle.

Accordingly, the present disclosure describes a workpiece processing apparatus comprising a plasma generator, a plasma chamber, and an extraction plate through which charged ions and reactive neutral particles are extracted. The workpiece processing apparatus extracts charged ions from the plasma chamber at a first selected extraction angle using a first mechanism and reactive neutral particles from the plasma chamber at a second selected extraction angle using a second mechanism. As described above, the first mechanism may be plasma sheath modulation or an electric field near the extraction aperture. The second mechanism may be the geometry of the neutral substance channel. Specifically, the orientation or inclination of the neutral mass channel 100 may determine the central extraction angle, while the aspect ratio of the neutral mass channel 100 may determine the distribution of the extraction angles.

Additionally, a workpiece processing apparatus is described that includes a plasma generator, a plasma chamber, and an extraction plate, wherein charged ions are extracted through a first aperture at a first selected extraction angle and reactive neutral particles pass through a second aperture at a second selected extraction angle, wherein the second aperture is different from the first aperture. As described above, the number of charged ions exiting through the neutral mass passage can be reduced by using a suppressor in combination with the neutral mass passage.

In certain embodiments, it may be advantageous to form a narrower distribution of reactive neutral particles. This can be achieved by collimation (collimation). Fig. 4A to 4C show an embodiment having a plurality of quasi-straight-lined neutral substance channels. Fig. 4A shows a first embodiment of a neutral substance passage 300 comprising a plurality of quasi-straight rows 310. As described above, the neutral substance channel 300 may be surrounded by the insulating material 330 to insulate the neutral substance channel 300 from the extraction plate 31. These quasi-straight rows 310 can be formed by forming the neutral passage 300 as an array or grid (raster) of smaller passages. Each of these smaller channels has a higher aspect ratio because the thickness of each smaller channel in the Z direction does not change, while the height in the Y direction decreases. In one embodiment, these aligned columns 310 can be formed by extending an electrically biased grid 320 through the thickness of the neutral material passage 300. This electrically biased grid 320 may be biased using a grid power supply 340. In certain embodiments, the quasi-straight rows 310 are formed to affect only the Y direction of the neutral material passage 300. In other embodiments, the quasi-straight rows 310 are formed to affect both the X-direction and the Y-direction of the neutral material passage 300.

Fig. 4B shows a second embodiment of a neutral mass passage 350 having a plurality of quasi-straight rows 360. As described above, the neutral substance channel 350 may be surrounded by the insulating material 380 to insulate the neutral substance channel 300 from the extraction plate 31. In this embodiment, the quasi-straight rows 360 are formed by inserting a plurality of thin strips 370 in the neutral material passage 300. These webs 370 may be of a conductive material or an insulating material. A conductive cup 385 may be disposed against an inner wall of the insulating material 380 and the conductive cup 385 may be in communication with a cup power supply 390. In certain embodiments, the quasi-straight rows 360 are formed to affect only the Y direction of the neutral material passage 350. In other embodiments, the quasi-straight rows 360 are formed to affect both the X-direction and the Y-direction of the neutral material passage 350.

Further, although fig. 4A to 4B show the neutral substance passage and the quasi-straight line as being orthogonal to the plane of the extraction plate 31, the present invention is not limited to this embodiment. The neutral substance channels and the collimating channels may be inclined with respect to a plane orthogonal to the extraction plate 31, if desired. For example, FIG. 4C shows the neutral passage 350 of FIG. 4B tilted slightly upward. For clarity, the cup power supply 390 is not shown, however the conductive cup 385 may be biased using the cup power supply 390. In addition, the neutral passage 350 shown in fig. 4B may also be inclined downward, if necessary. The angle of inclination is not limited by the present invention.

Fig. 5A to 5C show various embodiments of the extraction plate as viewed from the workpiece 90. Fig. 5A shows an extraction plate 31 with extraction openings 35 and two neutral substance channels 100. One neutral substance channel 100 is provided on each side of the extraction opening 35. The neutral substance passage 100 is rectangular in shape. The neutral substance passage 100 may have the same size in the X direction as the extraction opening 35. In certain embodiments, the neutral mass passage 100 may be smaller than the extraction aperture 35 in the Y-direction. In certain embodiments, the neutral mass passage 100 may be about 10mm away from the extraction aperture 35 in the Y-direction.

Fig. 5B shows a second embodiment of the extraction plate 31 when viewed from the workpiece 90. In this embodiment, the neutral substance channels 103 are staggered and disposed on the other side of the extraction aperture 35. This configuration can maintain greater mechanical strength in the extraction plate 31, but still deliver a sufficient flux of reactive neutrals to the workpiece and accommodate all of the above directional and collimation characteristics.

Fig. 5C shows a third embodiment of the extraction plate 31 when viewed from the workpiece 90. In this embodiment, the neutral mass passage 102 is circular to form a quasi-straight row, as described with respect to fig. 4A-4C. The neutral substance passage 102 is provided on either one of both sides of the extraction opening 35. This configuration can maintain greater mechanical strength in the extraction plate, but still deliver a sufficient flux of reactive neutrals to the workpiece and accommodate the directional and collimation characteristics described above.

In certain embodiments, the neutral mass channels in fig. 5A-5C may be respectively inclined toward the extraction aperture 35. In other words, the reactive neutral particles are directed towards the extraction opening 35, as shown in fig. 2. Thus, the reactive neutral particles are at + θ₂Is extracted through some neutral substance channels and is in-theta₂Is extracted via other neutral substance channels, where θ₂Is the second selected extraction angle.

In some embodiments, it may be desirable to be able to change the selected extraction angle. The first selected extraction angle may be modified, for example, by changing the electric field within the plasma chamber 30 or by moving the blocker 37 relative to the extraction aperture 35.

Fig. 6A-6B illustrate one embodiment that may be used to modify the second selected extraction angle. In this embodiment, the neutral substance passage 600 is accommodated within the rotatable member 610. The rotatable member 610 may be provided in the extracting plate 631. The rotatable member 610 may be a suitable material, such as SiO₂、SiC、SiN、Al₂O₃And the like. A dampener may also be provided within the rotatable member 610, which dampener mayAn electrically biased grid, screen or electrical cup. Fig. 6A shows that the rotatable member 610 is positioned such that the neutral substance passage 600 is perpendicular to the plane of the extraction plate 631. Fig. 6B shows the rotatable member 610 rotated upward relative to the position in fig. 6A.

Although the present invention illustrates the use of a separate neutral species channel, other embodiments are possible. For example, the blocker and extraction aperture may be designed to achieve a desired extraction angle of the reactive neutrals. Fig. 8A to 8I show various configurations. In these configurations, the width of the extraction apertures 835 in the extraction plate 831 and the distance between the stopper 837 and the extraction apertures 835 vary. In these configurations, the width of extraction aperture 835 is related to the width of stop 837. As the width of the extraction aperture 835 becomes narrower, the width of the stopper 837 also decreases. These configurations are presented as the distance between the stopper 837 and the extraction aperture 835 increasing to the right. The width of the extraction apertures 835 is reduced to move downward.

In fig. 8A, it is found that the average extraction angle of the fixed points in the plasma source is 50.8 °, and the distribution of the extraction angles is from 43.3 ° to 58.2 °. Thus, the spread (spread) is about 14.9 °.

Moving to fig. 8B, the distance between the stopper 837 and the extraction aperture increases. This reduces the average extraction angle to 49 deg., the distribution of extraction angles being from 35.7 deg. to 62.2 deg.. Thus, the spread is about 26.5 °.

In fig. 8C, the distance between the stopper 837 and the extraction aperture increases again. This reduces the average extraction angle to 41.2 deg., with the distribution of extraction angles being from 24.9 deg. to 57.5 deg.. Thus, the spread is about 32.6 °.

Thus, in general, as the distance between the stop 837 and the extraction aperture 835 increases, the average extraction angle decreases, but the angular spread increases.

In the configuration shown in fig. 8D, the distance between the stopper 837 and the extraction aperture 835 is the same as in fig. 8A, however, the widths of the extraction aperture 835 and the stopper 837 are reduced. This results in an average extraction angle of 45.3 deg., the distribution of extraction angles being from 35.5 deg. to 55.1 deg.. Therefore, the spread is about 19.6 °.

Moving down to fig. 8G, the widths of the extraction apertures 835 and the stoppers 837 are again reduced relative to fig. 8D. This results in an average extraction angle of 32.7 deg., the distribution of extraction angles being from 30.1 deg. to 35.3 deg.. Therefore, the spread is about 5.2 °.

Thus, in general, as the width of the extraction apertures 835 increases, the average extraction angle decreases, and the angular spread decreases.

Thus, manipulating the width of the extraction aperture 835 and the distance between the blocker 837 and the extraction aperture 835 provides another mechanism to control the extraction angle of the reactive neutral particles. Just as with the individual neutral species channels, this embodiment relies on the physical configuration of the openings, since the angle of extraction of reactive neutral species is largely dependent on line-of-sight optics. In other words, the reactive neutrals generally follow a path that presents a clear path from the plasma chamber to outside the extraction plate 831. Thus, by manipulating the width of the extraction opening 835 and the distance between the stopper 837 and the extraction opening 835, the extraction angle of the reactive neutral particles can be controlled.

In addition, modifying the width of the stop 837 independently of the width of the extraction opening 835 may provide another mechanism to control the extraction angle of the reactive neutrals.

In fig. 8A through 8I, the extraction angle of the charged ions depends on the shape of the plasma sheath and the electric field near the extraction aperture 835, as described above. Thus, two different mechanisms are used to control the angle of extraction of charged ions and reactive neutrals.

In another embodiment, the stopper 837 and the extraction opening 835 shown in fig. 8A to 8I may be used only for extracting neutral substances. In this embodiment, the blocker 837 may be biased at a positive potential to repel positive ions generated in the plasma. Further, in this embodiment, the extraction openings 835 may be similar to the neutral passage shown in fig. 2. Thus, the extraction apertures 835 serve as a passage for neutral species to exit at a second selected extraction angle. In this embodiment, the stopper 37 and the extraction opening 35 shown in fig. 1 may also be employed. In other words, two stoppers may be provided within the plasma chamber 30. The blocker 37 is used to manipulate the plasma sheath to facilitate extraction of charged ions through the extraction aperture 35 at a second selected extraction angle. The blocker 837 serves to provide a path for reactive neutral particles to pass through the extraction aperture 835 so that these neutral particles are extracted at a second selected extraction angle. Furthermore, since the blocker 837 and extraction openings 835 enable bimodal extraction of reactive neutrals, in some embodiments, only one neutrals channel is used.

Fig. 1, fig. 2, and fig. 5A to fig. 5C illustrate the use of a neutral substance channel 100 provided in the extraction plate 31. These neutral substance channels 100 are used to guide reactive neutral particles in a desired path. However, the neutral substance passage may be provided at other positions. Fig. 9 shows the extraction plate 931 and the stopper 937. As shown in fig. 2, the charged ions exit through the extraction aperture 935 in the form of a ribbon ion beam 60. However, in this embodiment, the neutral substance passage 900 is provided in the stopper 937. Similar to the previous embodiment, the geometric configuration of the neutral substance channel 900 is used to determine the extraction angle of the reactive neutral particles 901 from the extraction opening 935. Further, as described above, the neutral substance passage 900 in the stopper 937 may further include a suppressor, such as any one of the suppressors shown in fig. 3A to 3C. In addition, the neutral substance passage 900 provided in the stopper 937 may also be collimated as shown in the embodiments of fig. 4A to 4C.

The above disclosure and figures set forth embodiments in which reactive neutral particles are extracted from the same plasma chamber in which charged ions are generated. However, other embodiments may exist. For example, fig. 10 shows another embodiment. In this embodiment, neutral mass passage 100 communicates with neutral mass passage 1010. These neutral substance passageways 1010 may be in communication with one or more remote neutral substance generators 1000. In certain embodiments, the remote neutral species generator 1000 may be a plasma generator or other suitable device. The reactive neutral particles are then transported along the neutral material passage 1010 to the neutral material passage 100, thereby directing the reactive neutral particles toward the workpiece 90. In other words, the neutral substance passage shown in fig. 10 is separated from the plasma chamber 30. This embodiment may be advantageous in embodiments where long-lived reactive neutral species or metastable (meta) reactive neutral species are used. For example, fluorine atoms may be delivered to the neutral species channel 100 using this mechanism. Further, while fig. 10 is shown as a modification of fig. 2, it is to be understood that the remote neutral mass generator 1000 may be used with any of the other illustrated configurations.

The disclosed device has many possible applications. In one particular application, the apparatus is used to perform Directional Reactive Ion Etching (DRIE). In such applications, both charged ions and reactive neutral particles are delivered toward the workpiece at a selected extraction angle. These selected extraction angles enable etching of the material, in particular the material disposed in the trench. Fig. 7A shows a workpiece 700 to be etched. The workpiece 700 has a plurality of trenches 710, each having sidewalls 711 and a bottom 712. The workpiece may be any suitable material including, but not limited to, crystalline silicon, amorphous silicon, polysilicon, and silicon dioxide. The sidewalls 711 of each trench 710 may be coated with one or more films, which may be a dielectric 713 (e.g., silicon dioxide, silicon nitride, hafnium dioxide, etc.). The surface of the workpiece 700 may also be conformally covered by a liner 714, such as, for example, cobalt, tungsten, aluminum, copper, or titanium nitride. In certain embodiments, it may be advantageous to remove the liner 714 on the top surface and to a particular depth on the sidewalls 711.

In some embodiments, the removal of the liner 714 is accomplished by impacting the workpiece 700 with both charged ions and reactive neutral particles. In certain embodiments, a halogen-based feed gas (such as, for example, Cl) may be used₂、CF₄、CHF₃、CH₃F、C₂F₆、Br₂、BBr₃HBr or I₂) To form charged ions and reactive neutral particles. In other embodiments, a composition comprising O may be used₂、H₂Or NH₃To form charged ions and reactive neutral particles. In operation, a feed gas (which may be as listed above) is introducedOne or more of the species) is introduced into the plasma chamber 30. Radio frequency power is applied to the antenna 20 by a radio frequency power supply 27. Forming a plasma comprising charged ions (e.g., Cl)⁺) And reactive neutral particles (e.g., Cl).

In one non-limiting example, each trench 710 may be 100nm deep, and only 20nm of the top of the liner 714 will be removed. Additionally, the liner 714 will be removed from the top surface 715. To remove a portion of the liner 714 from the sidewall 711, the charged ions and reactive neutrals are measured by phi₁Strikes the workpiece 700 as shown in fig. 7A. If the angle at which these ions and reactive neutrals strike the workpiece is greater than phi₁The liner 714 on the sidewall 711 will not be etched to a proper degree. A larger angle (i.e., more horizontal) will etch less of the sidewall 711 because the top surface 715 of the adjacent trench will block ions and reactive neutrals from striking the sidewall 711.

Fig. 7A to 7B show a workpiece 700 during machining. In these figures, the workpiece 700 is moved to the left relative to the workpiece processing apparatus 10. Thus, the trench 710 on the left side of the figure has been etched, while the trench 710 on the right side of the figure is still covered by the liner 714.

FIG. 7A shows an appropriate amount of angle φ for etching the liner 714 from the sidewall 711₁. This angle is a function of the pitch (i.e., the distance between adjacent trenches), the aspect ratio of the trenches, and the amount of liner 714 to be removed. The angle phi used in FIG. 7A₁Is relatively large. Fig. 7B shows a workpiece 700 having grooves 710 positioned much closer to each other than the grooves shown in fig. 7A. Thus, the appropriate amount of angle φ for etching the liner 714 from the sidewall 711₂Phi ratio₁Much smaller. The apparatus disclosed herein is capable of forming this desired angle of reactive neutral particles by using neutral substance channels.

The above-described embodiments in the present application may have a number of advantages. First, directional reactive ion etching can be more efficient and effective when both charged ions and reactive neutral particles contact the surface to be charged. The angle of extraction of reactive neutral particles can be precisely controlled by using neutral species channels in a manner that may not be possible with conventional techniques. This precise extraction angle control enables dense features to be etched. Indeed, in some embodiments, the time to etch the sidewalls of the trench may be reduced by an order of magnitude or more than an order of magnitude due to the ability to accurately direct the reactive neutrals to the desired locations.

The scope of the invention is not limited by the specific examples described herein. Indeed, other various embodiments of the invention and various modifications to the invention will become apparent to those skilled in the art from a reading of the foregoing description and the accompanying drawings in addition to those described herein. Accordingly, such other embodiments and finishes are intended to fall within the scope of the invention. Moreover, although the invention has been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art will recognize that its applicability is not limited thereto and that the invention can be advantageously implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full breadth and spirit of the present invention as set forth herein.

Claims

1. A workpiece processing apparatus comprising:

a plasma generator;

a plasma chamber; and

an extraction plate having a first opening and a second opening;

wherein the workpiece processing apparatus extracts charged ions through the first opening at a first selected extraction angle using a first mechanism and reactive neutral particles through the second opening at a second selected extraction angle using a second mechanism, wherein the second opening is different from the first opening and the second opening includes a suppressor to minimize the charged ions passing through the second opening by neutralizing or repelling the charged ions,

wherein the first mechanism comprises a plasma sheath modulation or electric field proximate the first aperture, and wherein the second mechanism comprises a geometric configuration of the second aperture.

2. The workpiece processing apparatus of claim 1, wherein the suppressor comprises an electrically biased conductive grid disposed in the second aperture.

3. The workpiece processing apparatus of claim 1, wherein the suppressor comprises an electrically biased cup disposed about the second aperture.

4. The workpiece processing apparatus of claim 1, wherein the suppressor comprises a screen for neutralizing charged ions entering the second opening.

5. The workpiece processing apparatus of claim 1, wherein the second selected extraction angle is determined by an inclination of the second aperture relative to a plane orthogonal to the extraction plate, and wherein an angular distribution of the reactive neutrals centered at the second selected extraction angle is determined by an aspect ratio of the second aperture, the aspect ratio being defined as a length of the second aperture through the extraction plate divided by a height of the second aperture.

6. The workpiece processing apparatus of claim 1, wherein a blocker is disposed in the plasma chamber, and wherein the second selected extraction angle and the angular distribution of the reactive neutral particles centered at the second selected extraction angle are determined by a width of the second aperture, a width of the blocker, and a distance between the blocker and the second aperture.

7. The workpiece processing apparatus of claim 1, wherein the reactive neutral species are formed in a remote neutral species generator distinct from the plasma chamber and are conveyed to the second opening.

8. A workpiece processing apparatus comprising:

a plasma generator;

a plasma chamber; and

an extraction plate through which charged ions and reactive neutral particles are extracted,

wherein the workpiece processing apparatus extracts the charged ions from the plasma chamber at a first selected extraction angle via an extraction aperture disposed in the extraction plate using a first mechanism and extracts the reactive neutral particles from the plasma chamber at a second selected extraction angle using a second mechanism,

wherein the first mechanism comprises a plasma sheath modulating or electric field proximate to the extraction aperture, and wherein the second mechanism comprises a geometric configuration of a neutral species channel, wherein the neutral species channel is different from the extraction aperture such that the reactive neutral particles pass through the neutral species channel before exiting the plasma chamber.

9. The workpiece processing apparatus of claim 8, wherein the neutral substance passage is provided in the extraction plate.

10. The workpiece processing apparatus of claim 8, wherein the neutral species passage is disposed in a blocker disposed within the plasma chamber proximate the extraction aperture.

11. A workpiece processing apparatus comprising:

a plasma generator;

a plasma chamber;

an extraction plate comprising extraction apertures; and

a blocker disposed within the plasma chamber proximate the extraction aperture,

wherein the workpiece processing apparatus extracts charged ions as an ion beam through the extraction aperture at a first selected extraction angle using plasma sheath modulation or an electric field; and

wherein the reactive neutral particles pass through the neutral species channel at a second selected extraction angle, and

wherein the neutral species channel is disposed in the blocker such that the reactive neutral species pass through the neutral species channel in the blocker before exiting the plasma chamber.